Process for optically determining the meat-to-lard-ratio in for instance slaughtered animals

ABSTRACT

By a process for optically determining the meat-to-lard-ratio in for instance slaughtered animals, a probe is inserted perpendicular to the surface of the animal. This probe (7) comprises at least two light fibres (1, 2) opening on to the surface of the probe and communicating at the opposite end with means for transmitting and receiving red light of a predetermined wave length. The signals received are measured relative to a reference value automatically determined as the mean value of the lowest reflection values. This process is so sensitive that even the degree of marbling may be measured.

TECHNICAL FIELD

The invention relates to a process for optically determining themeat-to-lard-ratio in objects such as slaughtered animals or portionsthereof, by which process a probe with light conducting means in theform of at least one transmitter transmitting light of a predeterminedcolour and at least one receiver, is inserted substantiallyperpendicular to the surface of the object.

BACKGROUND ART

Probes of the above type are known. These probes are, however, not sosensitive that they can state the degree of marbling, i.e. the size anddistribution of lard enclosings in the meat, but only the lardthickness, cf. for instance Danish Pat. No. 109,246.

DISCLOSURE OF INVENTION

The object of the invention is to provide a process permitting such asensitive measuring that the degree of marbling may be measured.

The process according to the invention is characterised by the lightconducting means transmitting and receiving red light in a very narrowfrequency band about a predetermined wave length, the signalstransmitted being measured relative to a reference value automaticallydetermined. The narrow band width renders it possible to avoidirrelevant signals from the surroundings. The automatic determination ofa reference value implies an automatic adjustment as a consequence ofthe colour of the meat and the light of the surroundings. The apparatusis simplified due to the fact that manual adjustments are unnecessary.

Moreover according to the invention the wave length of the transmittermay be 0.93 μm±0.02 μm, preferably 0.93 μm±0.01 μm, and the receiver maybe sensitive at 0.93 μm too and be more broad-banded. In this manner thesignal-to-noise-ratio is improved.

Furthermore according to the invention the light transmitted may bepulse modulated, whereby the signal-to-noise-ratio is additionallyimproved.

The pulse modulation may for instance be a coded pulse modulation.

Furthermore according to the invention, the reflection versus thepenetration depth may be recorded in a memory, whereby a morecomprehensive signal treatment of the values measured is permitted.

Finally according to the invention, the insertion of the probe may beperformed in 256 steps, whereby the memory must comprise at least 256locations, thus providing an appropriate resolving power.

BRIEF DESCRIPTION OF DRAWINGS

The invention will be described below with reference to the accompanyingdrawing, in which

FIG. 1 illustrates a probe for carrying out the process according to theinvention,

FIG. 2 illustrates the reflection as function of the insertion of theprobe into a piece of meat, and

FIG. 3 is a rear view of a probe with three free cutting edges duringthe introduction, whereby furthermore the mouth of the light conductingmeans relative to the cutting edges is illustrated.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 illustrates a probe 7 to be introduced into a piece of meat. Thisprobe is used for optically determining the meat-to-lard-ratio includingthe degree of marbling of the object. The probe comprising at least twolight conducting means 1, 2 is introduced substantially perpendicular tothe surface of the object. The light conducting means in the form of twolight fibres 1, 2 open on to the side or at the spigot end of the probe7. Through a converter 3 converting light signals into electricalsignals, the fibres communicate with a calculating unit 4 recording thesignal for the reflection in a memory 5. The location in the memory 5,which is recorded together with the reflection value, is dedetermined onthe basis of the penetration depth x at the moment in question. Thepenetration depth stepwise registered may for instance be measured bymeans of a potentiometer 8 in the measuring instrument 6. The lightfibers 1, 2 are adapted to transmit and receive red light in a verynarrow frequency band about a predetermined wave length. In this mannerirrelevant signals from the surroundings are excluded. Furthermore, thevery narrow frequency band improves per se the signal-to-noise-ratio.

The values recorded as function of the penetration depth x may forinstance appear as illustrated in FIG. 2. The first portion of the curveillustrates the reflection outside the object. The next portionrepresents the layer of lard, whereas the final portion represents thelayer of meat. The points of the meat reflection at x₁, x₂, and x₃ thencorrespond to lard enclosings. The principle is now that the calculatingunit 4 receiving information concerning both the penetration depth andthe reflection on the basis of a number of the lowest measured valuesautomatically calculates a reference value. The lowest measured valuesare signals being for instance 10 times, optionally 5 times smaller thanthe greatest signals. The advantage by measuring the reflectionsrelative to this reference value is that adjustments are saved, wherebythe apparatus is less expensive and the measuring accuracy is improved.Furthermore, the colour of the meat, the light of the surroundings, andcomponent aging phenomena, if any, are automatically compensated. Theinformation disclosable after the signal treatment are first andforemost the degree of marbling, subsequently the location and size ofthe fatty tissues. The measuring process may be more sensitive by pulsemodulating, optionally CPM-modulating the light transmitted.

The light diodes used are of the type TEXAS INSTRUMENTS TIL 23 or 24.These light diodes are sensitive at the wave length 0.93 μm, the bandwidths being 0.04 μm and 0.02 μm, respectively. As receiver, a Si-phototransistor sensitive at the same frequency is employed.

The process and the apparatus according to the invention may be variedin many ways without deviating from the scope of the invention.

When the point of the probe penetrates the membranes separating theindividual muscles and fatty tissues, cf. FIG. 3, the membranes may as aconsequence of the friction between said membranes and the probe shaftbe pressed downwards and thereby cover for the light transmitter and thereceiver, said point of the probe being triangular and comprising threefree cutting edges. Just opposite the three cutting edges, the membranedoes not, however, abut the probe shaft, cf. FIG. 3, for which reason alocation of the light means opposite a cutting edge is of a decisiveimportance, whereby the light means are equally axially positioned.

In other cases too, the light means may open on to the same axialposition. As a result the measurements may be performed in the sameplane. When the light means do not open on to the same planeperpendicular to the longitudinal axis of the probe, the degree ofmeasurable layer thicknesses would be limited.

The probe 7 may for instance be of stainless steel.

We claim:
 1. A process for optically evaluating the meat-to-lard-ratioin slaughtered animals or portions thereof, comprising:inserting a probecomprising at least one light means including at least one transmittertransmitting light of a predetermined color and at least one receiver,said transmitter and receiver being located opposite or behind a cuttingedge of said probe, substantially perpendicularly to a surface of aslaughtered animal or portion thereof, transmitting red light in a verynarrow frequency band about a predetermined wave length, measuringreflected signals relative to a reference value automatically determinedas the mean value of the lowest value in a series of received signals,and recording reflection versus penetration depth.
 2. A processaccording to claim 1, wherein more than one light means is employed,said light means being located in substantially the same axial position.